The present invention relates to electric machines and, in particular, it concerns synchronous reciprocating electric machines and methods for their design.
Alternating current electric machines excited by permanent magnets or field windings are known in the literature as synchronous machines (rotating or linear). A rotating or running field generated by the system of windings attracts the systems of field poles (excited by windings or permanent magnets).
The speed of the movable part of electric machine is equal to speed of the rotating (running) magnet field. That is why these machines are classified as synchronous. Their speed does not vary with either an applied load or a supplied voltage, being instead fully determined by an external circuit frequency and the pole number. For generators, an induced voltage frequency depends upon the speed and pole number while the voltage depends upon the design of the windings.
It should be noted that, while the theory and design methods of rotating synchronous electric machines are well developed in the literature worldwide, the theory, calculation methods and constructions of reciprocating machine are all but absent from the literature.
There is therefore a need for efficient compound-moving-magnet synchronous machines which make maximal use of the available magnetic flux, for linear or arcuate reciprocating movement. It would also be advantageous to provide a method of designing compound-moving-magnet synchronous machines which would optimize the design parameters for any given application.